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Author Topic: Does Canon really have a Flagship Stills Camera?  (Read 30804 times)

neuroanatomist

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Re: Does Canon really have a Flagship Stills Camera?
« Reply #105 on: April 22, 2013, 09:38:56 AM »
dofmaster.com changes the CoC when it changes the sensor size, so it's of not much use because if the CoC stays the same, then the DoF stays the same.

Oh, I see.  This time we're holding CoC constant, meaning we're varying the enlargement factor, or maybe we're looking at different sized images?  Would you like to vary viewing distance, too, or should we have people with different visual acuity judge the two formats independently.

It's clear we have differing opinions, and clear to me who's correct. If you want to go on looking at single pixel output and compare different pictures to draw conclusions that are irrelevant for photographic images, you go right ahead. I'm done here.
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Re: Does Canon really have a Flagship Stills Camera?
« Reply #105 on: April 22, 2013, 09:38:56 AM »

Sella174

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Re: Does Canon really have a Flagship Stills Camera?
« Reply #106 on: April 22, 2013, 09:49:28 AM »
To come out with a meaningful figure across sensor sizes you have to standardise output. The "standard" DOF calculator assumes an 8"x10" print viewed at 12" and average eyesight. If you magnify a sensors output more to get to that 8x10 then you have to use a smaller CoC value, because you are enlarging it more.

Oh, I understand. It's totally wrong and completely skews the results, but I do understand.

... for the same lens from the same place a crop sensor image will return less dof than a FF camera if both images are uncropped

I thought it was the other way around.

You see, depending on how you work the figures a crop camera can be said to have more dof, less dof, or the same dof as a FF sensor.

Yip, it just depends on how you stack the deck and fiddle the maths.

... if you crop an image you decrease it's dof.

Huh?

Want an f1.2 image but only have an f1.8 lens? Stand back and crop.

Double huh? If you stand back, you have to refocus ... which means you change the distance ... which means your DoF changes.
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TrumpetPower!

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Re: Does Canon really have a Flagship Stills Camera?
« Reply #107 on: April 22, 2013, 10:03:46 AM »
To come out with a meaningful figure across sensor sizes you have to standardise output. The "standard" DOF calculator assumes an 8"x10" print viewed at 12" and average eyesight. If you magnify a sensors output more to get to that 8x10 then you have to use a smaller CoC value, because you are enlarging it more.

Oh, I understand. It's totally wrong and completely skews the results, but I do understand.

If you do, then nobody else does.

Let's try again.

The general idea in photography is that you will choose a particular location to achieve the perspective you wish, and then use your equipment to make an exposure that will optimize the quality of a print of a certain size.

If I read you right, that's completely bass-ackwards, and you expect the photographers to change perspective, composition, and now print size just so that they don't unfairly stack the deck against your favorite piece of equipment.

Perhaps you could take a step back and explain to the rest of us what, exactly, it is that you think you're comparing and why?

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b&

Sella174

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Re: Does Canon really have a Flagship Stills Camera?
« Reply #108 on: April 22, 2013, 10:05:48 AM »
Why should a photographer care more about comparing sensors than comparing camera systems? In what situation is the type of comparison you insist on making ever relevant to a photographer using a camera to create photographs?

Then why are members of the CanonRumors forum complaining about the "same" 18MP sensor in the latest cameras, or discussing if the upcoming 7D2 will have a 21MP sensor?
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TrumpetPower!

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Re: Does Canon really have a Flagship Stills Camera?
« Reply #109 on: April 22, 2013, 10:10:41 AM »
Why should a photographer care more about comparing sensors than comparing camera systems? In what situation is the type of comparison you insist on making ever relevant to a photographer using a camera to create photographs?

Then why are members of the CanonRumors forum complaining about the "same" 18MP sensor in the latest cameras, or discussing if the upcoming 7D2 will have a 21MP sensor?

A) Ask those who're complaining; and
ii) I thought we were comparing two different formats -- APS-C v 135 -- not different resolutions of the same format?

Somebody here is very, very confused, and I don't think that person is me....

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kyamon

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Re: Does Canon really have a Flagship Stills Camera?
« Reply #110 on: April 22, 2013, 10:15:07 AM »
... I never quite understood why people say that FF and APS-C have different DoF (provided the same optics, aperture, and distance to the object are used).

Marketing through misinformation, obfuscation, leading and derogation.

... then again, many people here seem to believe this too...


It's clear we have differing opinions, and clear to me who's correct. If you want to go on looking at single pixel output and compare different pictures to draw conclusions that are irrelevant for photographic images, you go right ahead. I'm done here.

This is not a matter of opinion, and you as a scientist in imaging know that. It is a matter of definition and standard. If you define DoF in purely optical terms then you have to define "focus" as a property that is independent of whatever sensor captures the image (and that sensor could be a human eye). As soon as you bring in the sensor you have to add further parameters to define for what conditions the DoF is compared. Once these parameters are defined, the case is clear again.

Things like cropping an image certainly don't change the DoF - it changes your framing and that is all. And for the same reason if you would take a FF sensor and cut out the centre part at the size of an APS-C sensor the DoF does not change - again, from a purely optical standpoint.

But that makes little sense from a photographers point of view, as has been pointed out previously...

Sella174

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Re: Does Canon really have a Flagship Stills Camera?
« Reply #111 on: April 22, 2013, 10:28:29 AM »
The general idea in photography is that you will choose a particular location to achieve the perspective you wish, and then use your equipment to make an exposure that will optimize the quality of a print of a certain size.

Correct.

If I read you right, that's completely bass-ackwards, and you expect the photographers to change perspective, composition, and now print size just so that they don't unfairly stack the deck against your favorite piece of equipment.

Erm, if dofmaster.com has chosen an 8x10 print as the "standard" for calculating the CoC used in their program, then they are now forcing everybody else into that standard.

An 18MP sensor can record finer details than an 8MP sensor (of similar size), therefore the 18MP image can be enlarged more whilst still retaining more detail than the 8MP image. So, "enlarging" to a fixed size is a flawed normalisation method. Besides, DoF is a characteristic of lenses, not sensors ... so again normalising different sensor sizes through enlargement to a fixed size produces flawed results.
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Re: Does Canon really have a Flagship Stills Camera?
« Reply #111 on: April 22, 2013, 10:28:29 AM »

TrumpetPower!

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Re: Does Canon really have a Flagship Stills Camera?
« Reply #112 on: April 22, 2013, 10:39:05 AM »
An 18MP sensor can record finer details than an 8MP sensor (of similar size), therefore the 18MP image can be enlarged more whilst still retaining more detail than the 8MP image. So, "enlarging" to a fixed size is a flawed normalisation method. Besides, DoF is a characteristic of lenses, not sensors ... so again normalising different sensor sizes through enlargement to a fixed size produces flawed results.

There is a great deal of misunderstanding in that paragraph. Too much for me to feel like trying to help you understand. Suffice it to state that you're conflating a great many variables with reckless abandon.

I'll just leave the matter (for now) by noting that this is all stuff covered in elementary photography (and physics / optics) textbooks and suggest that you take a trip to your local library (or bookstore) to get up to speed.

Cheers,

b&

Sella174

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Re: Does Canon really have a Flagship Stills Camera?
« Reply #113 on: April 22, 2013, 10:41:07 AM »
I thought we were comparing two different formats -- APS-C v 135 -- not different resolutions of the same format?

Nope, we're trying to discuss whether Canon has a "flagship" DSLR - and it seems nearly everyone agrees that the 1DX fits that bill - and why the lesser cameras aren't incremental in terms of features and capabilities. Oh, and those defending their Rebel-grade 6D's as being superior to the 7D ...  :P
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Sella174

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Re: Does Canon really have a Flagship Stills Camera?
« Reply #114 on: April 22, 2013, 10:48:59 AM »
There is a great deal of misunderstanding in that paragraph.

So a 7D (with its 18MP sensor) does not resolve more detail than a 30D (with its 8MP sensor)? See, Ken Rockwell was right ... megapixels don't matter!
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TrumpetPower!

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Re: Does Canon really have a Flagship Stills Camera?
« Reply #115 on: April 22, 2013, 11:25:26 AM »
Oh, and those defending their Rebel-grade 6D's as being superior to the 7D ...  :P

Oh. I see.

You think that the 7D has superior image quality to the 6D.

Well, enjoy that fantasy world you've built for yourself. But do be careful at zebra crossings....

Cheers,

b&

Albi86

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Re: Does Canon really have a Flagship Stills Camera?
« Reply #116 on: April 22, 2013, 12:21:07 PM »
... I never quite understood why people say that FF and APS-C have different DoF (provided the same optics, aperture, and distance to the object are used).

Marketing through misinformation, obfuscation, leading and derogation.

DoF is related to angle of view and aperture. To get the same angle of view at the same distance from the subject, on FF you need a longer focal length (1.6x if we consider a Canon APSC) than on crop.

Then, because f/stops are related to focal length, if you keep the same aperture on both systems you'll see that on crop you end up with a narrower iris. This is why you have more DoF ;)

kyamon

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Re: Does Canon really have a Flagship Stills Camera?
« Reply #117 on: April 22, 2013, 12:54:32 PM »
... I never quite understood why people say that FF and APS-C have different DoF (provided the same optics, aperture, and distance to the object are used).

Marketing through misinformation, obfuscation, leading and derogation.

DoF is related to angle of view and aperture. To get the same angle of view at the same distance from the subject, on FF you need a longer focal length (1.6x if we consider a Canon APSC) than on crop.

Then, because f/stops are related to focal length, if you keep the same aperture on both systems you'll see that on crop you end up with a narrower iris. This is why you have more DoF ;)

Provided you are comparing two photos that have the same framing. Which makes sense from a photographers point of view, I agree.
Basically all I had tried to point out in my previous posts was that this whole discussion is only because of different definitions. As some people said, this is all optics, and most of it has been known for almost 500 years. Wether we have dSLRs or not does not change any of this. But most of these statements about DoF or the required scaling of focal lengths on crop factors only make sense with very specific assumptions. The latter is only appropriate if you only look at an object at a particular distance - if you have a foreground and a background (assuming infinite depth of field here :) ) then the perspective will change, so the scaling factor does again not properly describe it.

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Re: Does Canon really have a Flagship Stills Camera?
« Reply #117 on: April 22, 2013, 12:54:32 PM »

Sella174

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Re: Does Canon really have a Flagship Stills Camera?
« Reply #118 on: April 22, 2013, 12:58:28 PM »
DoF is related to angle of view ...

In The Asahi Pentax Way Herbert Keppler explains why this is apparently so, but incorrect as well (pages 247-248 in the 8th edition).
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privatebydesign

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Re: Does Canon really have a Flagship Stills Camera?
« Reply #119 on: April 22, 2013, 12:59:08 PM »
... I never quite understood why people say that FF and APS-C have different DoF (provided the same optics, aperture, and distance to the object are used).

Marketing through misinformation, obfuscation, leading and derogation.

DoF is related to angle of view and aperture
. To get the same angle of view at the same distance from the subject, on FF you need a longer focal length (1.6x if we consider a Canon APSC) than on crop.

Then, because f/stops are related to focal length, if you keep the same aperture on both systems you'll see that on crop you end up with a narrower iris. This is why you have more DoF ;)

No it isn't, and this common misunderstanding is why people keep failing to get their heads around this.

Depth of field is a function of two metrics alone, reproduction ratio (how big the subject is projected onto the capturing device)  and aperture. Now if you want to make comparisons across sensor sizes you have to make a standard for reproduction size, it doesn't matter what the standard is, but if you don't you can't make relevant comparisons.

"DOF is determined by subject magnification at the film / sensor plane and the selected lens aperture or f-number." http://en.wikipedia.org/wiki/Depth_of_field

I would strongly suggest people stop talking crap and start reading and learning something authoritative about the subjects they seem so intent on teaching other people about.
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Re: Does Canon really have a Flagship Stills Camera?
« Reply #119 on: April 22, 2013, 12:59:08 PM »